Mild Steel Circular Hollow Section Pipes

Mild steel circular hollow section, also sold as CHS, MS pipe, ERW pipe or round tube, is the section to use where load comes from every direction or where the member has to twist without distorting. A round section has no weak axis, resists torsion better than any open or box section of the same weight, and presents less area to wind. Seen Steel supplies MS circular hollow sections and ERW pipe from ½" up to 12" nominal bore, cut to length and delivered to all seven emirates.

Sizes and weights

Pipe is ordered by nominal bore, which is a name, not a measurement. The outside diameter is fixed for each nominal size and the wall thickness changes with the schedule or series. The table shows the two specifications we are asked for most: ASTM A53 Schedule 40 and EN 10255 Medium. Weights are calculated at 7.85 g/cm³ for plain end pipe.

Standard length is 6 m. Note that in 2½", 5" and 6" the EN 10255 outside diameter differs from the ASTM one, so fittings and clamps for one will not always fit the other. Tell us which system your fittings are made to. For other sections and the weight formula, see the steel weight chart.

Standards and grades

• ASTM A53, Grade A or B, Schedule 40 as standard. The most widely used pipe specification in the UAE for structural and general service.
• EN 10255, in Light (L, L1, L2), Medium and Heavy series from ½" to 6". The successor to BS 1387 and still often called by the old name on site.
• EN 10219 and EN 10210, for structural circular hollow sections specified by outside diameter and wall rather than by nominal bore, in S275J0H or S355J2H.

For pressure piping, the line specification governs, and it may call for seamless pipe to ASTM A106 rather than welded A53. Send the specification with your enquiry. Our guide to steel grades covers how structural grades compare.

Light, Medium or Heavy

The EN 10255 series refer to wall thickness. Light pipe is the economical choice for handrails, fencing and non load bearing frames. Medium is the general purpose grade for structural use, scaffold style frames and most water and air services. Heavy is for threaded connections under higher pressure and for members that take impact or wear. If in doubt, Medium is the safe default.

Round, square or rectangular

Round pipe is the best choice for columns in open structures, handrails, bollards, posts and anything that twists. For beams and rails that span, a rectangular hollow section gives more stiffness for the weight, and square hollow section is easier to connect and clad, since flat faces weld and bolt more simply than curved ones.

Mild steel or galvanized

Black pipe must be painted or coated for outdoor use in the UAE. For fencing, handrails, shade structures and water services, hot dip galvanized pipe and hollow sections are the better choice and need far less maintenance.

Common applications

• Columns for canopies, sheds, carports and shade structures
• Handrails, guardrails, bollards and fence posts
• Bracing, trusses and space frames
• Pipe racks, supports and sleeves
• Water, air and general service lines
• Rollers, shafts and machinery frames

Cut to length and delivery

We supply 6 m lengths or cut to your list, and deliver to workshops and sites across all seven emirates, including Al Quoz, Jebel Ali, Mussafah, Sajaa and Al Hamra. Mill test certificates are supplied with the material.

What to send for a quote

• Nominal bore or outside diameter, and schedule, series or wall thickness
• Standard and grade, for example ASTM A53 Gr B Sch 40 or EN 10255 Medium
• Plain end, bevelled, or threaded and socketed
• Black or galvanized
• Quantity and delivery location

Frequently asked questions

What is the weight of a 2 inch Schedule 40 pipe?
About 5.44 kg per metre, or roughly 32.6 kg for a 6 m length.

Is 2 inch pipe 2 inches in diameter?
No. A 2" nominal bore pipe has an outside diameter of 60.3 mm. Nominal bore is a size name, not a measurement.

What is the difference between CHS and pipe?
Mostly the standard it is made to. Pipe standards such as ASTM A53 and EN 10255 size by nominal bore and are also used for fluid service. Structural CHS to EN 10219 or EN 10210 is sized by outside diameter and wall, with guaranteed structural grades.

What is ERW pipe?
Electric resistance welded pipe, made by rolling strip into a tube and welding the seam. It is the most common type of mild steel pipe used in construction.

Do you supply mill test certificates?
Yes, MTCs are issued with the material.

Send your pipe or circular hollow section requirement through the steel quote request form or on WhatsApp at +971 56 227 5722.

Supply and delivery

Circular hollow section is the one section where two different sizing systems are in daily use side by side, and getting the wrong one is an expensive mistake. Tell us whether you are working to a nominal bore and schedule, or to an outside diameter and wall thickness in millimetres, and the enquiry gets priced against the right thing.

Who buys CHS and pipe from us

• Fabricators making handrails, balustrades, barriers and bollards
• Structural contractors using CHS as columns, bracing and truss members
• Scaffold and access companies buying to a consistent outside diameter
• Civil contractors on piling, culvert and sleeve work
• MEP and plumbing contractors working to EN 10255 light, medium or heavy

Nominal bore or outside diameter

An ASTM A53 Schedule 40 pipe and an EN 10255 medium pipe of the same nominal size do not share a wall thickness, and neither matches a structural CHS specified by outside diameter. Three figures settle it: the system, the nominal size or outside diameter, and the wall thickness. Our steel weight chart carries the weights for each.

Galvanized or black

Anything outdoors in the UAE, and anything carrying water, is worth taking galvanized rather than black. For hot dip galvanized round sections see galvanized round pipes.

Where we deliver

Deliveries run to every emirate: Dubai, Abu Dhabi, Sharjah, Ajman, Ras Al Khaimah, Fujairah, Umm Al Quwain. Site and workshop deliveries are both standard.

To price a list, send it through the steel quote request form or on WhatsApp at +971 56 227 5722. The full product list shows everything we carry.